Roll feeder for excavating wheel



March 1, 1960 F. F. KOLBE 2,925,433

ROLL FEEDER FOR EXCAVATING WHEEL Filed Nov. 1:. 1957 4 Sheets-Sheet 1 INVENTOR.

BY fl dwmjhmwm k March 1960 F. F. KOLBE ROLL FEEDER FOR EXCAVATING WHEEL 4 Sheets-Sheet 2 Filed Nov. 13, 1957 F. F. KOLBE 2,926,438

ROLL FEEDER FOR EXCAVATING WHEEL 4 Sheets-Sheet 4 Z W/ E E am a 151% March 1, 1960 Filed Nev. 13, 195'! w- O wk United States Patent ROLL FEEDER FOR EXCAVATING WHEEL Frank F. Kolbe, Winnetka, Ill., assignor to The United Electric Coal Companies, Chicago, 111., a corporation of Delaware Application November 13, 1957, Serial No. 696,227

14 Claims. (Cl. 37-190) The present invention relates generally to excavating apparatus of the bucket wheel type and, especially to an improved roll feeder for transferring excavated material from the interior of the wheel to an endless conveyor belt or the like. The invention is an improvement over the roll feeder disclosed in my co-pending application, Serial No. 390,454, filed November 6, 1953, now Patent No. 2,826,839, granted March 18, 1958.

In bucket wheel excavators of the type to which the invention relates, the wheel is mounted for rotation in a vertical plane and an endless conveyor belt for conveying away the earth excavated by the wheel extends horizontally rearwardly from the side of the wheel in parallel relation thereto. The wheel is provided at its periphery with a plurality of buckets that cut into and scoop up large quantities of earth when the wheel is rotated. The buckets carry the earth upward to a point where the earth gravitates therefrom into the interior of the wheel, and means must be provided for discharging the excavated earth laterally from the interior of the wheel onto the conveyor belt.

Prior to the invention disclosed in my said co-pend'ng application, the means adopted for the purpose was an inclined slope sheet disposed within the interior of the wheel and inclined from adjacent the inner margin of the buckets downwardly toward the axle of the wheel and outwardly toward the conveyor belt. Such slope sheets suffered many disadvantages. First, clogging of the sheet, due to accumulation of earth materials thereon, necessitated frequent costly shut-down of the entire excavating apparatus to accommodate manual cleaning of the sheet. Secondly, the sheet imposed severe restrictions on wheel design, and particularly limited bucket width and the arc of bucket discharge because of the necessity for disposing the sheet at a high angle of inclination if clogging were to be minimized. Because the sheet had to have a steep slope, to cause the earth to pass to the belt with minimum sticking on the sheet, the buckets could be widened only if the diameter of the wheel were increased. Also because of the high angle thereof, the slope sheet did 'not absorb the full vertical force of the descending earth materials, with consequent severe abuse and short service life of the conveyor belt. Yet, the slope sheet, or means of equal strength, was required because of the weight, jagged edges and abrasive character of the earth, rocks, lumps of clay and frozen earth, and the like, discharging from the buckets.

In my aforesaid Patent No. 2,826,839, I have disclosed a solution to the problems incurred in the use of slope sheets, the solution being a roll feeder or roller conveyor comprising a plurality of positively driven rollers extending in a generally horizontal plane, or a plane inclined slightly to the horizontal, from the inner wall of the wheel to the adjacent edge portion of the belt just above the axle of the wheel. Being disposed substantially horizontal and immediately above the wheel axle, the roll feeder has greatly increased the are through which the buckets may discharge. The substantially horizontal disposition "ice of the rollers also permits any desired width of bucket without requiring any increase in wheel diameter. The rollers are rotated positively to move the excavated material in the direction of the belt and, due to their positive drive, are not subject to clogging. Shut-down time for cleaning is therefore minimized. The rollers are cylindrical and formed of steel and absorb the force of the excavated earth gravitating from the buckets, and the impact and shock consequent upon discharge of rocks and lumps, and they deposit the excavated earth relatively gently on the conveyor belt, thereby appreciably increasing belt life.

Thus, the roll feeder affords substantial advantages in terms of increased production, decreased maintenance and decreased shut'down time. However, any downtime is expensive when the following is kept in mind. Une machine of the character to which the invention relates, which may be said to be about average size in the particular art, is 360 feet long, 160 feet tall and 35 feet wide and includes a wheel 20 feet in diameter carrying eignt buckets eacn having a capacity of three cubic yards. The cost of the machine over its useful life, averaging working and idle time, is estimated to be $60.00 per hour, and shut-down of such machine results in id.ing not only that machine and its crew, but the crews and machines of working units employed in conjunction therewith. Thus, down time, even though substantially reduced by my earlier roller conveyor from that of the slope sheet equipped wheels, is still an exceedingiy expensive cost item.

The object of the present invention is to provide improvements on my earlier form of roll feeder, and particularly to provide an improved roll feeder substantially eliminating the occurrence on its account of downtime and increasing machine efficiency.

Specifically, it IS the object of the present invention to provide an improved roll feeder for excavating wheels characterized in that the peripheral speed of the rollers increases from the innermost roller to the outermost roller.

in my earlier form of roll feeder for wheel excavators, the rollers are all of the same diameter and driven at the same speed, and the inboard roller derives its power through the outboard rollers. In contemplating the problems occasioned with this unit, I noted that the inboard roller must assume a relatively large proportion of the force of the descending material and of the work in moving the material laterally, especially in overcoming the inertia of the material to lateral movement at right angles to the plane of rotation of the wheel. I conceived that if each outer roller were rotated at progressively greater speed than the next inwardly adjacent roller, the path of material egress from the inner rollers would be cleared and the inner rollers, and particularly the innermost roller, would derive proportionally greater power better to perform their specific functions, thereby to reduce damage to the rollers and increase the efficiency of drive. When this theory was put into practice, however, I discovered that both the reduction in damage and the increase in efficiency were considerably greater than had been expected, that the roll feeder per se has caused no down-time at all, that the rollers could be driven appreciably slower than had theretofore been possible and that the conveyor belt was loaded more uniformly than before. Specifically, my improved feeder, one embodiment of which has been in use for several months, has reduced the power requirement from horsepower to 30 horsepower, has reduced the speed of the innermost roller from 154 r.p.m. to about 58 r.p.m., has increased roller bearing and drive gear life to an extent not yet ascertainable, but at least manifold, consistently loads the belt centrally thereof, and has yet to cause, on its own account, shut-down of the excavator.

These surprising results are difficult to explain, but I believe they are attributable principally to operation of the rollers at progressively increasing speeds. In retrospect, and upon analysis of the operation of my improved roll feeder, I offer, in addition to the factors above noted, the following partial explanation. When, as in my earlier device, the rollers are all of the same size and driven at the same speed, a certain amount of excavated earth, including stones and gravel, accumulates in the V-shaped space between adjacent rollers. The downward force of rotation produced by the inboard one of two adjacent rollers on this material, plus the force of gravity is greater than the upward force exerted thereon by the outboard one of the two rollers, and there is, therefore, no tendency for this material to be dislodged. When the roll feeder is loaded with excavated earth, the material in said V-shaped space is perhaps wedged by the load thereon tightly against the two rollers, thereby applying a braking force against them. This would result in loss of power, severe abrasion of the rolls and flexure of the rolls intermediate their bearing supports due to the tendency of wedged stones to separate the rollers. By driving the outer one of two adjacent rollers at a sufficiently greater peripheral speed than the inner roller, as provided according to the present invention, the outer roller continuously tends to lift excavated material out of the V-shaped space between the rollers, thereby to counteract the downward loading on the material and prevent wedging thereof into said space. Moreover, it appears likely that the continuous outward movement of material relative to the V-shaped space between the rolls forms a flowing wall of material immediately above the rollers, which moves in the direction of the conveyor belt and assists in driving descending material toward the belt before it contacts the rollers thereby reducing the load on the rollers and roller wear.

The specific object of the invention, namely the provision of a roll feeder in which the peripheral speed of the rollers increases from the innermost to the outermost roller, may in view of the foregoing explanation, be accomplished by driving rollers of the same diameter at progressively increasing speeds or by providing rollers of progressively increasing diameters driven at the same number of revolutions per minute. The objects of the invention include the provision of both types.

It is a particular object of the invention, however, to provide an improved roll feeder of compact, sturdy and economical construction comprising a plurality of rollers of the same diameter, and means for rotating each of the rollers outwardly of the innermost roller faster than the next inwardly disposed roller.

A further object of the invention is the provision of improved drive means for effecting rotation of the rollers in the manner described.

A still further object of the invention is the provision of improved roll feeders as above described including a raised bead, preferably a helix, of hard wear-resistant metal on the surface of each roller to localize roller wear on the bead and to accommodate build-up of a cushioning layer of earth on each roller below the outer surface of the head to shield the surface of the roller from wear.

Other objects and advantages of the invention will become apparent in the following detailed description of preferred embodiments of the invention.

Now in order to acquaint those skilled in the art with the manner of making and using the improved roll feeder of my invention, I shall describe, in connection with the accompany drawings, preferred embodiments of the feeder and preferred manners of making and using the same.

In the drawings, wherein like reference numerals indicate like parts:

Figure 1 is a side elevation of the digging wheel of an excavator of the type to which the present invention relates, the view showing the Wheel and belt conveyor and a preferred embodiment of my improved roll feeder associated therewith;

Figure 2 is essentially a plan view of the apparatus shown in Figure 1, the wheel being illustrated in section to reveal my roll feeder and the drive means for the feeder having been added;

Figure 3 is a fragmentary vertical section of the wheel showing a preferred embodiment of the drive means for the feed rollers;

Figure 4 is a side view of the preferred embodiment of my roll feeder, the view being taken substantially on line 44 of Figure 2 and showing the outboard roller, its bearings and drive connection in longitudinal section;

Figure 5 is a cross-sectional view of the drive means and bearing assembly provided between each roller and its drive shaft; and

Figure 6 is a fragmentary vertical section of a digging wheel of modified construction equipped with a second embodiment of my improved roll feeder.

Referring now to the drawings, and particularly to Figures I-3, I have illustrated the digging wheel end of an excavating apparatus of the character to which the invention relates. As shown, the excavator includes a vertically adjustable and horizontally oscillatable digging ladder 10 rotatably mounting at its free end a digging wheel 12. The wheel includes a pair of spaced coextensive rims 14 carrying a plurality of circumferentially spaced digging buckets 16, suitably eight in number. The buckets are preferably any one of the type disclosed in my co-pending applications, Serial No. 585,335, filed May 16, 1956, now Patent No. 2,834,127, granted May 13, 1958, and Serial No. 586,806, filed May 23, 1956, now Patent No. 2,834,128, granted May 13, 1958, which buckets are each characterized by a back wall consisting of a flexible and movable mat 18 capable of gravitating downwardly when the bucket is in its upper position to facilitate complete discharge of excavated material therefrom. The wheel is open at one side and closed at its other side by a vertical wall 20 by means of which the wheel is mounted on its axle 22. To rigidify the wheel and the mounting thereof on the axle, the wall 22 preferably includes a conical central portion 24, as shown.

Adjacent the open side of the wheel, the ladder 10 mounts an endless conveyor belt 26 which extends rear wardly from the side of the wheel in generally parallel relation thereto. The conveyor may lead directly to a point of disposal, or may lead to other conveyors or the like that ultimately lead to a point of disposal. The conveyor 26 is supported at its forward end by an idler pulley 28 which mounts the belt with its carrying run extending over the wheel axle 22 and its return run extending under the wheel axle. Rearwardly of the pulley, the carrying run of the bolt is preferably supported by troughing idle-r assemblies (not shown) to provide a troughed surface for reception of excavated earth, as illustrated in Figure 3. The belt may suitably be driven at its opposite end by any conventional means.

In use, the wheel is rotated in the direction illustrated by the arrow in Figure 1 and moved horizontally into a bank of earth to cause the buckets 16 thereof to scoop up large quantities of earth and to carry the excavated earth upwardly. To insure retention of earth in the buckets during their upward travel, the wheel is equipped at its forward portion with a stationary plug 30 which effectively closes the bottom of each bucket during its movement upwardly to a point slightly above the horizontal plane of the wheel axle. At this point, the plug terminates to permit the excavated earth to gravitate out of the respective bucket into the interior of the wheel. The excavated material drops from each bucket onto the roll feeder of the present invention, which is indicated generally at 40, and this instrumentality feeds the earth laterally out of the interior of the wheel onto the upper run of the conveyor 26, which then carries the material rearwa'rdly and deposits the same on a spoil pile.

The wheel 12, in one embodiment with which I have worked extensively, is 20 feet in diameter and each bucket thereof has a capacity of about three cubic yards. Consequently, in the operation of the wheel, in all seasons of the year and in all climates, the buckets scoop up a wide variety of earth including sand, loose dirt, mud, clay, frozen earth, rocks, stones and the like. As each bucket reaches discharge position, the excavated earth therein gravitates onto the roll feeder 49 with substantial impact, especially when each bucket discharges a large lump of clay or frozen earth, or a large rock. The roll feeder is required to absorb the impact consequent upon this vertical drop and then to transfer the excavated material relatively gently onto the conveyor belt irrespective of the character of the material, i.e., loosely divided or in one large lump. It is apparent therefore that the nature of the service requires the feeder to meet rigid specifications.

The roll feeder 40 of the present invention embodies the essential principles of my earlier feeder as disclosed in Patent No. 2,826,839, the same including a series of cylindrical rollers 41, 42, 43 and 44 extending from the interior of the wheel to a position above the conveyor. The rollers, which may be of any required or desired number, are disposed above the axle 22 of the Wheel beneath the buckets 16 and are rotated so that their upper surfaces move toward the belt. The innermost roller 41 of the series, herein referred to as the inboard roller, is disposed adjacent and parallel to the vertical wall 20 of the wheel, and the remainder of the rollers span the space between the inboard roller and the adjacent edge portion of the conveyor 26. The rollers are mounted parallel and in close proximity to one another and are preferably staggered vertically downward in the direction toward the belt. By virtue of this relationship, the upper surfaces of the rollers define a ramp inclined downwardly toward the belt to facilitate the intended transfer of the excavated earth, and each roller slightly overlaps the next outwardly disposed roller to mitigate against loss of earth and to increase the efiiciency of transfer of material from one roller to the next. The outboard one of the rollers is disposed to the exterior of the wheel and above the inner edge portion of the conveyor belt, all in accordance with the teaching of my Patent No. 2,826,839.

The roll feeder of the present invention is particularly characterized in that the rollers 41, 42, 43 and 44 are rotated at different peripheral speeds. In the preferred embodiment, the rollers are all of the same diameter and are rotated progressively faster from the inboard to the outboard roller. Driving of the rollers in this manner is accomplished by the means illustrated in Figures 2-5, which means includes a prime mover 46, suitably an electric motor, and a speed reducer 48, both of which are mounted on the digging ladder outside of the wheel 12 and in rearwardly spaced relation thereto. The output shaft of the reducer is connected, preferably by a chain and sprocket drive 50 and a clutch 52, to a shaft 54 which generally parallels the belt 26 and passes to the open side of the wheel 12.

The shaft is connected at its opposite ends by universals 56 to the sprocket drive 50 and to the input shaft 58 of a gear box 60. The gear box 60 constitutes a support for one end of the feed rollers 41, 42. 43 and 44, and the box itself extends transversely of the wheel 12, belt 26 and feed rollers from the belt into the interior of the wheel. The input shaft 58 is rotatably supported in the gear box by bearings 61 and is aligned axially with and coupled directly to the outboard feed roller 44, whereby the roller 44 is driven at the same speed as the shaft 54. Specifically, the shaft 58 includes, at the side of the gear box opposite the shaft 54, a flange 62 which is connected by a split collar 64 to a complementary flange 66 provided on the adjacent end of a stub shaft 68. The stub shaft 68 extends into the interior of the outboard roller 44 and at its opposite end carries a toothed drive element 70 forming part of an improved drive coupling and bearing assembly constituting the subject matter of the co-pending application of John J. Huey, Serial No. 696,240, filed November 13, 1957. The toothed element 70 is meshed with a complementary toothed element 72 which is keyed or otherwise secured to the roller 44, the assembly includ' ing cushioning pads 74 between the meshed teeth to absorb and prevent transmission to the gear box of the shocks and impacts to which the roller is subjected in use. The inner toothed element 70 also includes a spherical bearing surface 75 on which the outer element 72 is mounted for universal movement, by means of rings 76, to accommodate flexure and displacement of the roller, as occasioned by impact loading thereof, Withont imparting strain to the gear assembly. At its opposite end, the roller 44 is provided with a stub shaft 78 rotatably mounted in a pillow block bearing 80.

The gear box 60 rotatably supports, by means of bearings similar to those indicated at 61, a number of shafts similar to the shaft 58, the said shafts, which are indicated at 91, 92 and 93, being of the same num' ber as and aligned respectively with the remaining rollers 41, 42 and 43. The rollers are all of the same construction and diameter as the roller 44 and are coupled to the respective shafts 91, 92 and 93 by mating flanges and collars like the flanges 62 and 66 and the collar 64. The rollers 41, 42 and 43 are thus supported for rotation at one end by the gear box 60. At their opposite ends, these rollers are mounted in the same manner as the roller 44 in a pillow block bearing 80. The gear box 60 is mounted on a base 84 and the pillow blocks are mounted on a base 86, thereby to facilitate installation of the roll feeder on the digging ladder 10 with the rollers positioned as previously described.

The input shaft 58, within the gear box 60, has keyed thereto a first gear 104 and the shafts 91, 92 and 93 have keyed thereto corresponding gears 101, 102 and 103. respectively. The gears 101-104 constitute a set of drive gears and the same are coupled together for rotation in the same direction by a set of idler gears consisting of gears 105, 106, and 107, each journalled on an idler shaft mounted in the gear box 60. The object of the invention, as previously stated, is to drive the rollers at progressively increasing peripheral speeds from the inboard roller to the outboard roller. The purpose of the gears 101107, therefore, is to decrease progressively the speed of rotation of the rollers from the outboard to the inboard roller, since the rollers are all of the same diameter and the outboard roller and its gear 104 are the prime movers. To this end, either or both sets of gears may be of increasing diameter from the outboard to the inboard rollers, or other modifled arrangements may be adopted. I prefer to form the idlers 105107 all of the same diameter and to make the gears 104, 103, 102, and 101, of progressively increasing diameters, respectively. In a specific embodiment which has given excellent service, I have utilized a gear 104 having a 10 inch pitch diameter, a gear 103 having an 11 inch pitch diameter, a gear 102 having a 12 inch pitch diameter, a gear 101 having a 13 inch pitch diameter. and idlers 105-407 each having a pitch diameter of 10 inches.

In this specific embodiment, 1 have rotated the shaft 54, and thus the outboard roller 44, at about 75 r.p.m., which results in the roller 43 being rotated at about 68 r.p.m., the roller 42 at about 62 r.p.m., and the roller 41 at about 58 r.p.m. The rollers in this structure are 13% inches in diameter, thereby to afford peripheral speeds in the order of about 262, 238, 217, and 203 feet per minute, respectively. I have found these speeds of operation with the described size of roll feeder to produce optimum results in the excavator previously referred to, wherein the wheel, which is 20 feet in diameter, is rotated at about 10 to 12 rpm. and carries eight buckets, each having a capacity of about 3 cubic yards. The rollers operate with great efiiciency at low power, about 30 horsepower, and rapidly feed the excavated earth discharging from the buckets centrally onto the conveyor belt, thereby to effect uniform loading of the belt. The ability of the described roll feeder to withstand the abuse to which the same is subjected is outstanding. In several months of use, the specifically described embodiment of the feeder has not, on its own account, caused shutdown of the excavator.

Relative to the ability of the roll feeder to Withstand abuse, I have provided on the peripheral surface of each roller a raised bead 110 of wear-resistant metal, suitably welding rod. The head is secured to each roller in the form of a helix, but the configuration adopted is not, to my observation, critical. The rollers are positioned relative to one another in such manner that the raised beads on adjacent rollers are in close proximity, but the peripheral surfaces of the rollers per so are slightly spaced. The beads 11!] thus accommodate build-up on the surface of each roller of a thin layer of earth material, such as mud or clay, and this layer of earth serves as a protective cushion for the rollers to shield the peripheral surfaces thereof from excessive wear. Thus small stones, gravel and the like are considerably less likely to cause damage to the rollers than was the case in my earlier form of roll feeder. Each bead 110 also performs a cleaning or scraping function relative to adjacent rollers to prevent excessive accumulation of earth thereon and to assure optimum functioning of the rollers. Accordingly, roller wear is localized on the bead, which is readily replaced or restored as compared to replacing a roller. In the use to which my improved roll feeder has thus far been put, substantially the only maintenance work thereon has been addition of bead material on the rollers to compensate for the wear of the bead. This maintenance is quickly effected when the excavator is shut-down for other purposes and does not, on its own account. result in down-time.

Referring again to Figure 3, it is to be observed that the conical reinforcing means 24 provided at the central portion of the wheel 12, in the wheel structure illustrated, extends into the interior of the wheel. Because of this wheel construction, the roll feeder 40 must be spaced somewhat from the wall. and cannot be positioned immediately adjacent thereto. To close the space thus left between the wheel proper and the roll feeder, the stationary plug of the wheel includes a plug plate 31 consisting of a plurality of inclined plates for funneling descending excavated earth onto the rollers. To shield the gear box 60 and the drive shafts from excess accumulation of earth, and to protect the gear box from damage. the plug plate 31 also includes inclined plates 32 extending over the gear box.

In other wheel constructions, such as shown in Figure 6, wherein the conical portion 24 is disposed to the exterior of the wheel, the roll feeder can be positioned closely adjacent the vertical wall 20 of the wheel and the plug plate 31. with the exception of plates 32, can be of considerably reduced size and extent.

In Figure 6, l have also illustrated a modified form of the roll feeder of the invention that is distinguished from the form above described by rollers of different diameters. in this embodiment, the feed rollers, indicated at 41a. 42a, 43a and 44a, are of progressively increasing diameters, whereby all of the rollers may be driven at the same number of revolutions per minute and yet afford progressively increasing peripheral speeds. In such structure. gears corresponding to the gears 101- 107 previously described could suitably be identical, thereby to simplify the gear box. For overall convenience, economy and size reduction, however, I prefer the 8 embodiment of my invention first described, especially since that embodiment simplifies installation and service in the field.

in either embodiment thereof, the roll feeder of the present invention affords an economical, practical means of sturdy construction performing in a most facile manner the function of transferring excavated earth from the interior of the wheel onto the conveyor belt. The roll feeder imposes substantially no limitation on wheel design. especially bucket width, and facilitates complete discharge of each bucket over a wide arc of its rotational path of movement. The rollers absorb completely the impact of the earth discharged from the buckets and transfer the earth relatively gently onto the conveyor belt. Roller wear is mitigated to a substantially complete extent. The feeder is operated at very low power and slow speed, thereby further to mitigate damage and wear due to excess friction. Yet, the feeder loads the conveyor centrally and uniformly. Accordingly, it is apparent that the objects of the present invention are attained in an economical and practical manner.

While I have shown and described what I regard to be the preferred embodiments of my invention, it will be appreciated that various changes, rearrangements and modifications may be made therein without departing from the scope of the invention, as defined by the appended claims.

I claim:

1. A roll feeder for transferring excavated earth laterally from the interior of an excavating wheel onto an adjacent discharge conveyor, comprising a plurality of substantially parallel rollers including, relative to the wheel, an inboard roller and an outboard roller, and means for rotating said rollers at progressively inceasing peripheral speeds from the inboard roller to the outboard roller.

2. A roll feeder for transferring excavated earth laterally from the interior of an excavating wheel onto an adjacent discharge conveyor, comprising a plurality of substantially parallel rollers including, relative to the wheel, an inboard roller and a plurality of rollers disposed successively to the outboard side of said inboard roller, and drive means for rotating said rollers including means for rotating each of the rollers to the outboard side of said inboard roller at a peripheral speed greater than that of the next inwardly disposed roller.

3. In excavating apparatus including a digging wheel carrying at its periphery a plurality of buckets for scooping up earth and discharging the excavated earth downwardly into the interior of the wheel and a conveyor outside of the wheel for conveying away the excavated earth, a roll feeder for feeding the excavated earth from the interior of the wheel onto the conveyor comprising a plurality of substantially parallel rollers including, relative to the wheel, an inboard roller disposed Within the interior of the wheel and an outboard roller disposed above the edge portion of the conveyor adjacent the wheel, and drive means for rotating said rollers including means for rotating each of the rollers disposed successively to the outboard side of said inboard roller at a peripheral speed greater than that of the next inwardly disposed roller.

4. In excavating apparatus including a digging wheel carrying at its periphery a plurality of buckets for scooping up earth and discharging the excavated earth downwardly into the interior of the wheel and a conveyor outside of the wheel for conveying away the excavated earth, a roll feeder for feeding the excavated earth from the interior of the wheel onto the conveyor comprising a plurality of substantially parallel rollers including, relative to the wheel, an inboard roller disposed within the interior of the wheel and an outboard roller disposed outside of the wheel above the edge of the conveyor adjacent the wheel, means outside of the wheel for rotating said outboard roller, and motion transmitting means operatively connecting each of the other rollers to said outboard roller for rotating each of the said other rollers at a peripheral speed less than that of the next outwardly disposed roller.

5. For use in excavating apparatus including a digging wheel carrying at its periphery a plurality of buckets for scooping up earth and discharging the excavated earth downwardly into the interior of the wheel and a conveyor outside of the wheel for conveying away the excavated earth, the improvement comprising a roll feeder for feeding the excavated earth from the interior of the wheel onto the conveyor comprising a plurality of substantially parallel generally horizontal rollers including an inboard roller to be disposed within the interior of the wheel adjacent the side thereof opposite the conveyor and an outboard roller to be disposed outside of the wheel above the edge portion of the conveyor adjacent the wheel, the upper surfaces of said rollers lying substantially in a common plane that is inclined downwardly from the inboard roller to the outboard roller, each of the rollers inwardly of the outboard roller slightly overlapping the next outwardly disposed roller, drive means spaced from the wheel for rotating said outboard roller, and a gear train extending from said outboard roller into the interior of the wheel and coupling each of the rollers inwardly of the outboard roller to said outboard roller for rotating each of the said rollers in the same direction and at a peripheral speed less than that of the next outwardly disposed roller.

6. In excavating apparatus including a digging wheel carrying at its periphery a plurality of buckets for scooping up earth and discharging the excavated earth downwardly into the interior of the wheel and a conveyor outside of the wheel for carrying away the excavated earth, a roll feeder for feeding the excavated earth from the interior of the wheel onto the conveyor comprising a plurality of substantially parallel rollers of substantially the same diameter including an inboard roller to be disposed within the interior of the wheel and an outboard roller to be disposed outside of the wheel above the edge portion of the conveyor adjacent the wheel, drive means spaced from the wheel for rotating said outboard roller, and a speed reducing transmission extending from said outboard roller into the interior of the wheel and coupling each of the rollers inwardly of the outboard roller to said outboard roller for rotating each of the said rollers slower than the next outwardly disposed roller.

7. In an excavating apparatus, the combination comprising a digging wheel having an axle and having a plurality of excavating buckets at its periphery which buckets are adapted to discharge downwardly from their upper positions into the interior of the digging wheel, a conveyor positioned outside of said wheel, a series of rollers extending into the interior of the wheel for receiving downwardly discharging excavated material from the buckets and for conveying it outwardly of the wheel to said conveyor, said rollers being disposed a short distance above the axle of the wheel and extending across the interior of the wheel to receive discharged material from each bucket throughout a wide arc of its rotational path, and drive means for rotating said rollers including means for rotating each of the rollers to the outboard side of the innermost roller of the series at a peripheral speed greater than that of the next inwardly disposed roller.

8. In an excavating apparatus, the combination combination comprising a digging wheel having an axle and a plurality of excavating buckets at its periphery which buckets are adapted to discharge downwardly from their upper positions into the interior of the digging wheel, a conveyor positioned outside of said wheel for carrying away excavated material, a series of rollers extending into the interior of the wheel for receiving downwardly discharged excavated material from the buckets and for conveying it outwardly of the wheel to said conveyor, said rollers being disposed a short distance above the axle of the wheel and including an inboard roller disposed within the interior of the wheel and an outboard roller disposed outside of the wheel above the edge portion of the conveyor adjacent the wheel, drive means for rotating said outboard roller, and transmission means coupling said outboard roller to the other of said rollers for rotating said rollers at progressively increasing peripheral speeds from the inboard roller to the outboard roller.

9. A roll feeder for transferring excavated earth laterally from the interior of an excavating wheel onto an adjacent discharge conveyor, comprising a series of rollers of substantially the same diameter including, relative to the wheel, an inboard roller and an outboard roller, and drive means for rotating said rollers progressively faster from the inboard roller to the outboard roller.

10. A roll feeder for excavating wheels comprising a series of ro'lers of substantially the same diameter including, relative to the wheel, an inboard roller and an outboard roller, drive means for rotating said outboard roller, and motion transmitting means coupling each of the rollers inwardly of the outboard roller to said outboard roller, said motion transmitting means including a set of drive gears connected to respective ones of the rollers and a set of idler gears between the drive gears, the gears of one set being all of the same diameter and the gears of the other set being of progressively increasing diameters from said outboard roller to said inboard roller, whereby said rollers are rotated progressively faster from said inboard rolier to said outboard roller.

ll. A roll feeder for excavating wheels comprising a plurality of substantially parallel rollers including, relative to the wheel, an inboard roller and a pluraity of rollers disposed successively to the outboard side of said inboard roller, each of said rollers including a raised bead of wear-resistant material on the peripheral surface thereof, said rollers being positioned with the beads on adjacent rollers disposed in close proximity to one another, and drive means for rotating said rollers including means for rotating each of the rollers to the outboard side of said inboard roller at a speed greater than that of the next inwardly disposed roller.

12. In excavating apparatus including a digging wheel carrying at its periphery a plurality of buckets for scooping up earth and discharging the excavated earth downwardly into the interior of the wheel and a conveyor outside of the wheel for carrying away the excavated earth, a roll feeder for feeding the excavated earth from the interior of the wheel onto the conveyor comprising a plurality of substantially parallel generally horizontal rollers including an inboard roller to be disposed within the interior of the wheel and an outboard roller to be disposed outside of the wheel above the edge portion of the conveyor adjacent the wheel, drive means spaced from the wheel for rotating said outboard roller, and motion trans mitting means extending from said outboard roller into the interior of the wheel and coupling each of the rollers inwardly of the outboard roller to said outboard roller for rotating each of the said rollers at a peripheral speed less than that of the next outwardly disposed roller, each of said rollers carrying a raised bead of wear-resistant material on the peripheral surface thereof, said rollers being positioned with the beads on adjacent rollers in close proximity, said beans accommodating build-up of a cushioning layer of excavated earth on each roller to shield the peripheral surface of each roller from wear, the bead on each roller cleaning the rollers adjacent thereto and limiting the thickness of said cushioning layer of excavated earth.

13. In excavating apparatus as set forth in claim 4, said motion transmitting means connecting each of the said other rollers to said outboard roller for rotating each of the said other rollers at substantially the same number of revolutions per minute as said outboard roller, said rollers from the inboard roller to the outboard roller being of progressively increasing diameter.

14. A roll feeder as set forth in claim 1, wherein said means rotates said rollers at substantially the same number of revolutions per minute, and said rollers are of progressively increasing diameter from the inboard roller to the outboard roller.

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